A spore syringe is a syringe with spores of a mushroom in sterilized water.
The inoculation of the substrate is generally done with the help of a spore syringe. Theoretically it is possible to inoculate the substrate directly with the spores of a print, but in general these are too dry to be able to germinate. To get around this you can let the spores dehydrate in sterilized water and absorb them with a spore syringe. The spore water in the syringe can then be used to inoculate the substrate.
1 cc of a spore syringe should be enough to grow mycelium. A bigger amount can speed up the growth, though.
A flawless sterilization technique is essential for making spore syringes.